A computerized data base had been developed since 1975, which contains all hemodynamic and angiographic data, operations performed, survival statistics and major complications following either corrective or palliative operations for various types of acquired and congenital heart diseases. The data base contains approximately 3700 patients operated upon since the Clinic of Surgery, NHLBI, was founded in 1953. The Cardiology Branch is currently entering preoperative patients in an expanded data base which is being integrated with the Surgery data base.